apr_src_dir and find_apr.m4

[Patrick Welche <pr...@newn.cam.ac.uk>]

In the old days, apr lived in httpd/srclib. Now it can be anywhere, but ../apr
is a sensible alternative, hence buildconf's good choice of:

  apr_src_dir="srclib/apr ../apr"

Let's say source directories are /zzz/httpd and /zzz/apr. buildconf will
happily find the apr source in ../apr, and copy ../apr/build/find_apr.m4
to (/zzz/httpd/)build/find_apr.m4. The trouble is that find_apr.m4 looks
for apr in /usr /usr/local /usr/local/apr /opt/apr /usr/local/apache2
but not in ../  . 

The attached patch seems to get me further.

(Now I'm in apr trying it to buildconf with a modern libtool..
rather tricky as you at least need AC_CONFIG_MACRO_DIR and a few
more libtoolish .m4 files to sinclude..)

Cheers,

Patrick